Device for computing compound angles



July 10, 1945.

Filed Feb. 26, 1944 for.

Patented July 10, 1945 UNITED, STATES PATENT OFFICE John M. Petrov, Cleveland, Ohio Application February 25, 1944, Serial No. 524,136

'7 Claims.

The purpose of this invention has been to pro-' vide a simple and easily operable computing device for facilitating the mechanical computation of compound angles where the sizes of two angles are known and those of the remaining two angles are unknown.

The common method pursued today is to determine the unknown angles by trigonometric computation, in conjunction with tables giving trigonometric functions of angles. These computations obviously require time and care in the making. The computer of my present invention is designed to eliminate mental calculation and enable quick mechanical determination of the sizes of the unknown angles desired. This result is effected by simple manipulation of certain movable dials and a movable protractor, to set the same preliminarily in accordance with-two known angles, the setting of said parts mechanically adjusting others of them to assume posi-' tions of the reading of the unknown angles.

For a full understanding of the present invention, reference may be had to the following description in conjunction with the" accompanying drawing, in which: i

Figure 1 is a longitudinal horizontal sectional view of my computer taken about on the line I-I of Figure -3, looking downwardly.

Figure 2 is a diagram of angles later referred to in order to exemplify the operation of the computer.

Figure 3 is a front elevation of thedevice, the base portion broken away and. in section to show the base dial and mounting or axis means there- Figure 4 is a side view of the computer looking toward the same from the right as seen in Figure 3.

Figure 5 is a side view looking toward the computer from the left, or in direction opposite that of the view of .Figure 4. v

r Figure 6 is a fragmentary enlarged view of the detail of the scales of the three stationary protractors not fully illustrated in the other views.

with the protractor 3 intermediate its upper and lower ends. 4

Mounted onthe base I by means of an axis rear face of the supporting dial I6.

pin 4 threaded at its lower end to receive a holdrecess I2 in the under side of the base dial 6 and limits the turning movement of the dial 6 to a little more than degrees.

Mounted on the upper side of, and preferably integral with, the dial 6, is a standard I3 having its upper edge curved on an arc and provided at said edge with the main protractor I4. The

standard I3 carries the horizontal axis pin I5, perpendicular to the axis pin 4, and rotatably attaching to the front face of the standard I 3 the indicating and. protractor supporting dial I6. The dial I6 is perpendicular to the base dial 6 and is also limited in rotation to a little more than 90 degrees 'by the pin H on the standard I3, said pin engaging an arcuate recess I8 in the A nut I9 holds the pin I5 and dial I'6 in position on the standard I3, permittin rotating of the dial I6 for adjustment of its vernier 20 on the fiat 2|, relatively to the protractor l4. Pin I5 may operate in the bushing 22. Nut 35 secures the dial I 6 in position.

' Offstanding from the front face of the dial I6 is a boss 23 bored to provide a bearing receiving the bushing 24 in which is carried the stepped diameter bearing pin 25, the smaller end 25a. of which enters, and is pin-locked at 25b, 9, socket member 26a in the right upper portion of the swinging protractor 26. The member 26 at its left upper portion has a sleeve like bearing 2! that receives the left and larger end 250 of the pin- 25, the middle portion of. the latter being directly rotative in the bushing 24 previously mentioned. The space between the parts 260. and 21 is just sufficient to snugly receive the boss 23 alined with the parts 26a and 21.

The pin 25 thus provides an axis for the protractor 26 which axis is perpendicular to the verticle axis pin 4 and to the horizontal axis pin I5. Continuations of the lines of the axis of the parts 6, I5 and25 will intersect, as apparent from the drawing, when the parts are in their normal zero positions as read on the protractors.

The swinging protractor'26 has its body portion in the form of a thin web or vane, the curved 28 carried by a journal pin 25 to which it is interlocked by cross pin 30. The pin 29 is connected, through an opening and bushing 3| in the side member 2, with the side dial 32 having the fiat 33 provided with the Vernier 34, the latter to cooperate with the protractor 3 previously described. As seen in Figure 3, the arm 28 has a fiat 28a provided with the vernier 34 that coacts with the protractor 26 which is movable relatively to the arm 28, and by swinging movement rotates the latter. Or the protractor 26 may be swung by turning of the arm 28 by the dial 32. Turning of the dial 32 is limited by the pin 36 and recess 31.

The construction of my computing device being understood according to the foregoing description, its method of use may be exemplified by referring to Figure 2, which is a diagram disclosing a problem of compound angles.

In using the device, see diagram of Figure 2, the angle A will be read on the base protractor ID. The angle B will be read on the main protractor M. The angle C will be read on the side protractor 3, The angle D will be read on the swinging protractor 26.

The normal positions of the various dials 6, I6, 32, will be at zero on the coacting protractors; the swingin protractor will be at zero on the vernier 34 of the arm 28.

It. will be assumed that the angles A and B are known or given, and the angles C and D are to be ascertained.

The first step is to set the dial l6 to the angle B read on the protractor M. This will efiect, incident to vertical movement of the protractor 26, the same reading on the said protractor 26 as is obtained by dial [6 on protractor 14.

The second operation is to set the dial 6 at the angle A on the protractor 10. The turning. of base dial 6 will simultaneously cause the swinging protractor 26 to rotate about its axis 25, and cause rotation of the arm 28, thus correspondingly rotating the side dial '32.

By the above operation of the protractor 26 with the coincident movement of the dial 32,-

upwards the protractor 26 according to the sizes of the angle C read on dial 32, and angle D read on the protractor 26, the dials 6 and 16 may beoperated to give the readings for previously un known angles A on dial 6' and B on. dial l6.

Given any two angles, after setting the appro priate dials, or protractor 26, tothe readings of such angles, the twounknown angles may be mechanically determined by the movement 01 the remaining dials, or remaining dial and protractor 26, as the case may be.

It will be thus seen. that my device is readily usable for finding angles, according to the following. combinations A and B given; C and D may be found. A and C given; B and D maybe found. A and D giveny B and C may be found. B and C given; B and -D given; C and D given;

A- and B may be found.

A and 13- may be; .found/ A and C may be. found. 1

In reference to the first example of operation herein given, instead of setting the dial l6 first for the angle B, if the protractor 2B is swung to a horizontal position, dial 6 may be turned to the reading of angle A to efiect arcuate movement of the protractor 26, and the unknown angle read ings thus obtained on the dial 32 and the protractor 26.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In an angle computer of the class described, in combination, a base, a protractor thereon, a base dial rotative about a vertical axis on said base, and having a Vernier coacting with said protractor, a standard extending upward from the base dial, a main vertical dial rotative on said standard about an axis perpendicular to the axis of the base dial, a protractor on the standard, a Vernier on the main dial coacting with the last protractor, a side dial supported in a plane perpendicular to the base dial and having a Vernier thereon, a side member on the base supporting the side dial, a protractor on the side member coacting with the Vernier of the side dial, a swing-; ing protractor carried by the main dial and have ing its axis perpendicular to the axis of the main dial and angularly shiftable with the main dial about the axis of the latter, a turning arm connected to the side dial and having a vernier coacting with the swinging protractor, and means connecting said turning arm to the last mentioned protractor whereby swinging movement of the latter transmits rotation to the side dial.

2.- A computer as claimed in claim 1, characterized in. that the connecting means is formed to cause movement of the swinging protractor whenthesidedialis turned for an angle reading.

3. A computer as claimed in claim 1, wherein the main dial is provided with a bearing parallel with its computing face and in a plane inter-v secting. the base dial axis, the swinging protractor axis being mounted insaid bearing.

4. A computer as claimed in claim 1, in which the swinging protractor is of generally arcuate form. having its curved edge slidingly interlocking with the turning arm to establish the connection therewith.

5'. A computer as claimed in claim 1, in which theaxis of the side dial is rotative about the axis. of the main dial, and the swinging protractor is;

swingable at an angle to the plane of the main dial.

6. A computer as described, comprising a manipulatable base dial having a vernier, "a manipulatable vertical main dial having a vernier, a manipu-latable side dial having a vernier, protractors cooperative with the verniers of the dials, the main and side dials arranged perpendicular to the base dial, and the axes of the dials I in continued lines meeting at acommorr intersection point'in at least one position of all: the dials, a swinging protractor normally parallel to thev maindiaLdisposedin the plane ofand interlocked with the axis-of the side dial, and having its axis parallel to the face of the maindial andv in theplanes ofthe axis of the base and: main; dials, and a Vernier associated with the s'idedial coacting withthe-swinging protractor.

7. An instrument of the class described, comprising aplurality of protractors including three. rotatable. dial: membershaving their respective projected. axes ofrotation normally intersecting-s at a common point and perpendiculartm each-f other when the dials are each in their 'aemsbtting positions, a calibrated protractor member carried by one of the dial members and bodily movable with the latter about its axis, said protractor member being pivotally connected to the dial member on which it is carried for swinging movement relative thereto about an axis always perpendicular to the axis of the dial member, and

the protractor member being slidably and rotatably connected with one of the other dial members on the axis of the latter for coordinating the swinging movements of the protractor member 5 with the rotative movements of the respective dial members.

JOHN M. PETROV. 

